Process control systems, like those used in chemical, petroleum and/or other processes, typically include one or more field instruments or devices for measuring and/or controlling different aspects of the process control system. Field devices may include, for example, sensors, switches, transmitters, valve controllers, etc., that perform process control functions such as level sensing, temperature sensing, valve control operations, etc.
Field devices typically have an operating temperature or operating temperature range that defines the temperature(s) at which the device operates most effectively. For example, a field device may have an operating temperature range of −52° C. to 85° C. If the field device is exposed to temperatures outside of this range, the operability and/or operating life of the field device decreases. Some field devices such as, for example, electronic field devices, are particularly susceptible to temperatures outside of their operating temperature range. For example, digital valve controllers, pressure transducers and other digital sensors typically have elastomeric moving parts, and when these field devices are exposed to temperatures that are outside of their operating temperature range, the elastomeric parts suffer increased wear and, thus, the operating life of the field device is reduced.
Many process control systems are located outdoors. As a result, the field devices of the process control system are exposed to the climate/environment where the process control system is located. In some locations, this results in exposure to climates that produce relatively high and/or low temperatures. Therefore, field devices that have operating temperature ranges that do not cover the range of temperatures at the process control plant are likely to suffer increased wear and, thus, decreased operating lifespan.
The figures are not to scale. Instead, to clarify multiple layers and regions, the thickness of the layers may be enlarged in the drawings. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used herein, the terms “coupled” and “operatively coupled” are defined as connected directly or indirectly (e.g., through one or more intervening structures and/or layers).